Hydraulics don't return the pedal. If something's STUCK, there may be a return problem. Otherwise, it's probably the pressure plate fingers, since they act as the return mechanism.
But first check all the mechanicals - pedal box bushings, pedal box itself, arm/pushrod bushing, etc. Arm to the pushrod may not be clocked correctly. Is there a lot of slop / free play in the pedal?
Of course, check the firewall as described in this thread. One possibility is with the firewall moving, the master pushrod is getting out of line, and it's binding when trying to return.
Edit - one possibility with the hydraulics is a LOT of air in the system. Possible result - when the fork pushes back, it compresses the air rather than moving the fluid and pushing the pedal back up.